Road vehicles may be designed to travel through a body of water to a finite depth, which may be referred to as a maximum wading depth. Beyond this limit there is a risk that the vehicle engine may be damaged for example by the ingestion of water through the engine air intake and/or the vehicle electronics may be damaged by coming into contact with the water. Identifying that a vehicle has entered a wading situation or is in a wading event is advantageous so that control systems of the vehicle can be deployed.
Driver judgment is required when entering water at wading depth and this may require a consideration of not only the vehicle ground clearance, but also factors such as the location of the engine air intake. A vehicle driver does not generally know the depth of water the vehicle is about to enter or the nature of the terrain below the water surface. This is particularly so in low visibility conditions (dirty water, low-light, heavy rain, fog). It is recommended that a survey of the terrain is taken by wading through water on foot, but factors such as, the variability of the terrain; low visibility conditions; inconvenience to the driver; and driver impatience may result in a driver attempting to traverse water without knowledge of the water depth and therefore without being able to take appropriate precautions.
In WO/2012/080439 (PCT/EP2011/072998) (incorporated herein by reference) and WO/2012/080440 (PCT/EP2011/072999) (incorporated herein by reference) to the present applicant, systems for detecting that a vehicle is wading are described. It is disclosed in WO '439 that two series of ultrasonic transducers may be disposed across front and rear bumpers of a vehicle respectively. Immersion of the ultrasonic transducers in water is used to confidently determine that the vehicle is immersed in water, at least up to the height of the sensors. The sensors being positioned on the bumper are disposed at a height suitable for indicating that the vehicle is in a wading situation. In WO '440 another system for detecting wading is disclosed, in which a change in the time of flight, wavelength or amplitude of an acoustic pulse emitted and received by sensors of the system is used to detect the presence of water about the sensors.
In WO/2012/080429 (PCT/EP2011/072986) (incorporated herein by reference), also to the present applicant, a control system for a wading vehicle is described, wherein a vehicle, having a wading sensor adapted to identify wading above a predetermined depth of water, comprises a control system adapted to implement one or more vehicle control strategies upon detection of wading by said sensor.
In WO/2012/080438 (PCT/EP2011/072997) (incorporated herein by reference), also to the present applicant, a system is disclosed that upon detecting wading by means of a sensor, (such as that described in WO/2012/080439 (PCT/EP2011/072998) and WO/2012/080440 (PCT/EP2011/072999)) a downwardly facing ultrasound transducer is used to estimate a wading depth (D) of the water in which at least a portion of the vehicle is disposed.
In GB1202617.5 (incorporated herein by reference), also to the present applicant, a system is disclosed for determining vehicle wading depth and/or attitude by measured distances between range-finding transducers mounted in the door mirrors and the surface of water through which the vehicle is wading.
The present invention seeks to provide a further improvement for land-based vehicles, that may travel through water, by providing a system operative to take preventative or pre-emptive action to prepare and/or protect a vehicle that has entered into water or that is possibly about to enter into water well before a maximum wading depth limit of the vehicle is reached. Advantageously, the systems and methods of the present invention seek to predict that a vehicle may be about to enter into a wading event or has just entered into a wading event. Prior to the vehicle being disposed in water at a wading depth and well before the vehicle enters water close to the maximum wading depth, the systems and methods of the present invention prepare the vehicle. Preferably, the systems and methods of the invention prepare the vehicle for wading in advance of part-submersion of the vehicle body in water. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.
In this specification, the term wading relates to travel of a land-based vehicle through water of a depth that is sufficient to require that the vehicle driver take appropriate precautions. To distinguish a wading event from a vehicle driving through a shallow puddle, in some situations wading depth may be defined as water of 200 mm or more in depth. In some situations water at a level of the front or rear wheel hubs may be indicative of a vehicle in water at wading depth. In some situations wading depth may be defined as the point at which a water contact sensor is immersed in water. However, the depth at which it is determined that a vehicle is wading (sometimes referred to as a threshold wading depth) may be determined by the vehicle design and it is therefore not possible to define a threshold wading depth that is appropriate for all vehicles. Similarly, the permissible maximum wading depth of a vehicle is determined by the vehicle design.
In this specification the term control threshold depth is used to define a depth of water, optionally relative to a vehicle in normal ride height that is optionally below or close to the threshold wading depth for a vehicle. In some situations control threshold depth may be defined as water of about 100 mm to about 200 mm or more in depth. In some situations, control threshold depth may be defined relative to the height of a tail pipe outlet of an exhaust system or other vehicle components and control threshold depth may be defined as at least 20 mm below the opening of vehicle exhaust tailpipe outlet.
Throughout the specification reference is made to the term water. It will be understood that in the context of a land-based vehicle driving through water, the term “water” is intended to encompass all liquid or fluidic media that a land-based vehicle may drive through and is not limited in its interpretation to pure H2O. For example, as used herein water may mean, but not limited to: a muddy river bed; sea-water; a ford; and dirty water in off-road terrain.